Effects of Cold Application on Chest Tube Removal Pain in Heart Surgery Patients.

Background
Chest tube removal is considered a painful technique, which may not respond well to palliative therapies. There are no standard procedures or guidelines to manage the pain associated with chest tube removal. This study aimed to examine the effects of cold application on pain reduction during and after chest tube removal.


Materials and Methods
This randomized controlled trial was conducted on 90 hospitalized patients, undergoing heart bypass surgery at the intensive care units where at least a pleural chest tube was inserted. The patients were randomly divided into two groups (45 samples per group). In the cold application group, an ice bag was placed at the designated point for 20 minutes before chest tube removal, while only routine interventions were applied for chest tube removal in the control group. Pain severity was measured in the groups before, during, and 15 minutes after chest tube removal, using the visual analogue scale. Repeated measures ANOVA test was applied for data analysis.


Results
There was no significant difference in the baseline pain score between the groups (P= 0.18). However, there was a significant difference in terms of pain severity score between the cold application (3.58±1.09) and control (4.73±0.86) groups during chest tube removal (P< 0.001). On the other hand, there was no significant difference between the groups regarding the score of pain severity at 15 minutes after chest tube removal (P= 0.38).


Conclusion
Cold application, as a nonpharmacological intervention, may contribute to the alleviation of cryotherapy-related pain.


INTRODUCTION
Cardiovascular diseases (CVDs) are among the most debilitating diseases, accounting for the highest rate of mortality worldwide. According to statistics, CVDs lead to death in more than 16 million people annually (1,2).
Cardiac surgery is the most frequent therapeutic intervention for ischemic and cardiac valve diseases (3).
According to Texas Heart Institute, thousands of patients undergo cardiac and vascular surgeries in the United States every day (4). Also, 25 thousand heart surgeries are conducted in Iran per annum (5).
It is necessary to insert a chest tube in all types of heart surgeries in order to maintain the function of the heart and lungs and prevent pneumothorax, hemothorax, and pleural effusion. A chest tube is generally removed within 24 to 48 hours after cardiac surgery when the volume of secretion is less than 100-150 cc, and respiratory sounds are normal (6). Removal of a chest tube is a painful and frustrating experience for patients. Considering the chest tube tenacity to the surrounding tissues, its separation from the adjoined tissues is painful (7).
Medium to severe pain has been reported by patients during cryotherapy (CTR), while there are no standard procedures or guidelines to manage CTR-related pain (6,7). Nurses do not generally employ any interventions to reduce CTR pain and do not realize when physicians remove the chest tube (8). Alleviation of pain caused by painful interventions, such as CTR, is usually based on the administration of narcotic drugs and nonsteroidal antiinflammatory drugs (NSAIDs). Although these drugs are highly efficient in pain alleviation, studies have shown that CTR is still a painful procedure for patients (9 Convenience sampling method was applied to assign samples to the groups; the participants had an equal chance of assignment to each of the groups. Figure 1 presents the study flow diagram. A data recording checklist, consisting of two parts, was used for data collection. The first part was used to record demographic data (10 questions). Also, a checklist was developed to review relevant literature; its content validity was confirmed by 10 faculty members from Iran University of Medical Sciences. The second part of the checklist evaluated pain severity, using a visual analogue scale (VAS). In this tool, a score of zero indicates no pain, while a score of 10 presents the worst pain imaginable.
Accordingly, the participants indicated the severity of pain on VAS. Overall, numerous studies have used this scale to measure pain severity in heart surgery patients (7,(14)(15)(16).
In the present study, the participants were familiarized with VAS instructions and methods before CTR.
Surgery was performed by one surgeon, and surgical The pain score was measured by VAS in the two groups before, during, and 15 minutes after CTR.
The collected data were analyzed using descriptive tests in SPSS version 21. Descriptive statistics were used to summarize the demographic information. Chi square and t test were also used to compare demographic data.
Repeated measures ANOVA was applied to compare pain scores between the groups at different intervals. In addition, ANOVA test was applied for comparing pain scores between the groups at any time interval. P-value less than 0.05 was considered statistically significant.

RESULTS
In the present study, 90 eligible subjects were divided into the cold application and control groups. The cold application group received cold therapy before CTR, while the control group received routine interventions according to the ward policies. In a total of 90 participants, two patients from the cold application group and one patient from the control group were excluded for having a pain score above seven. After excluding these cases from the survey, data from 87 patients were finally analyzed. Based on the findings, gender, age, BMI, history of chronic pain, history of analgesic use, and chest tube insertion had no effects on pain due to CTR in the cold application and control groups (P> 0.05). The mean pain severity scores of the groups are presented in Table 2 and

DISCUSSION
Chest tube removal is considered a painful and debilitating experience for all patients (7). However, there are no standard procedures or guidelines to manage CTRrelated pain (17). It is proposed that treatment with nonpharmacological methods, such as cold therapy, can alleviate the pain caused by irritating procedures. Cold  (8,13,14,18).
In line with the present study, several investigations have shown that cold application is effective in relieving pain during CTR (7,14,18,19). In our study, pain severity during CTR was significantly lower in the cold application group, compared to the controls. This finding is consistent with the results of a study by Demir and Khorshid (7), in which 90 patients with chest tubes were randomized and assigned to cold application (20 minutes), placebo, and control groups; pain severity was measured by VAS. All patients received pain medications before CTR. The pain scores significantly decreased in the intervention group.
One can assume that use of an ice bag for 20 minutes accounts for the consistent results, as the bag needs to be applied for at least 20 minutes to induce favorable cryogenic effects (20).
On the other hand, Sauls reported cold application to be ineffective in reducing pain caused by CTR (15). This discrepancy can be explained by differences in the parameters evaluated in the current study. Also, the shorter duration of ice bag application ( It is hoped that the present findings promote future studies in this area. It is recommended to conduct a study with a larger sample size on CTR-associated pain in nonheart bypass surgery patients in order to confirm the present findings.

CONCLUSION
The results of this randomized controlled trial suggest that cold application, as a nonpharmacological intervention, may temporarily contribute to the alleviation of pain caused by CTR.